JP2021055748A - Insulated rolling bearing - Google Patents

Abstract

To provide an insulated rolling bearing that can prevent electric corrosion and prevent a gap from being generated between a shaft and a bearing washer.SOLUTION: An auxiliary bearing 21 includes: an inner ring 22 and an outer ring 23; multiple balls 24 interposed between the inner and outer rings; and an insulted bushing 28 fitted into an inner peripheral part of the inner ring 22. The insulted bushing 28 includes: a substantially cylindrical metal substrate 28a; and a resin layer 28b formed at an inner peripheral surface of the metal substrate 28a, and is fitted while bringing the metal substrate 28a side into contact with the inner peripheral part of the inner ring 22.SELECTED DRAWING: Figure 2

Description

The present invention relates to insulated rolling bearings, and more particularly to insulated rolling bearings used in refrigerant compressors.

The positive displacement refrigerant compressor is widely used in various fields as a compressor for refrigerating and air-conditioning equipment. In recent years, there has been increasing interest in energy reduction, and efficiency improvement is required in various industries. In particular, air conditioners that are closely related to the living environment are attracting a lot of public attention, so there is a need to develop highly reliable products that can achieve lower costs and higher efficiency. The number of variable-speed operations that drive electric motors has increased, and the efficiency has been improved compared to conventional constant-speed refrigerant compressors.

In the refrigerant compressor using the above inverter, the drive current (input current from the inverter to the motor) at high load is larger than that of the conventional constant speed type refrigerant compressor. Therefore, the voltage (shaft voltage) generated in the crankshaft that rotates integrally with the electric motor tends to increase. As the shaft voltage increases, the potential difference between the inner ring and the outer ring of the rolling bearing that supports the crankshaft increases, and as a result, an increase in the current flowing through the rolling bearing is caused. This current causes corrosion called electrolytic corrosion on both the inner and outer raceway surfaces of the rolling bearing and the rolling surface of the rolling element, which lowers the reliability of the refrigerant compressor.

The refrigerant compressor described in Patent Document 1 is known as a conventional refrigerant compressor that prevents the occurrence of such electrolytic corrosion. In this refrigerant compressor, an insulating sleeve made of an insulating material is provided between the crankshaft and the auxiliary bearing that rotationally supports the auxiliary shaft portion on the anti-compression mechanism portion side of the drive portion on the crankshaft. As a result, electrolytic corrosion of the bearing is prevented, and the inexpensive structure suppresses bearing damage due to bearing electrolytic corrosion and insufficient amount of oil supply to improve the reliability of the refrigerant compressor.

In addition, as rolling bearings with other measures against electrolytic corrosion, rolling bearings filled with conductive grease (see Patent Document 2) and rolling bearings in which an insulating film is directly formed on a raceway ring (see Patent Document 3) are used. Are known.

Japanese Unexamined Patent Publication No. 2018-40261 Japanese Unexamined Patent Publication No. 2004-263836 Japanese Unexamined Patent Publication No. 2002-295483

In the refrigerant compressor described in Patent Document 1, the insulating sleeve is fitted on the inner diameter side of the inner ring by means such as press fitting. However, since the insulating sleeve and the crankshaft and the insulating sleeve and the inner ring rotate relative to each other, the insulating sleeve is liable to be worn. As a result, a gap is created between the crankshaft and the inner ring, which may cause vibration and abnormal noise of the entire compressor.

Further, in a refrigerant compressor, since the rolling bearing is used in a liquid refrigerant in which refrigerating machine oil and a refrigerant are mixed, in the rolling bearing described in Patent Document 2 above, conductive grease is eluted to prevent electrolytic corrosion. There is concern that it will decline.

Further, in the rolling bearing described in Patent Document 3, an insulating film made of synthetic resin is formed by injection molding on the anti-track surface of the outer ring or the inner ring. In injection molding, the molten resin is injected at a high pressure, and the resin shrinks due to cooling and solidification, so that the shape of the raceway surface formed with high precision may deteriorate. Therefore, it is necessary to increase the thickness of the raceway ring on the side where the insulating film is formed, and it is difficult to reduce the size of the device.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an insulated rolling bearing that can prevent electrolytic corrosion and prevent a gap between a shaft and a raceway ring.

The insulated rolling bearing of the present invention includes an inner ring and an outer ring, a plurality of rolling elements interposed between the inner and outer rings, and an insulating bush fitted to the inner peripheral portion of the inner ring or the outer peripheral portion of the outer ring. An insulating rolling bearing, the insulating bush has a substantially cylindrical metal base material and a resin layer formed on an inner peripheral surface or an outer peripheral surface of the metal base material, and the insulating bush is the metal. It is characterized in that the base material side is brought into contact with the inner peripheral portion of the inner ring or the outer peripheral portion of the outer ring and fitted.

The insulating bush is a wound bush having a cut portion in a part in the circumferential direction.

The base resin of the resin layer is a polytetrafluoroethylene (PTFE) resin. Further, the resin layer is characterized by containing 10% by mass to 30% by mass of glass fibers with respect to the entire resin layer.

The insulated rolling bearing is used in a refrigerant compressor, and is characterized by being a bearing that rotationally supports a shaft that is rotationally driven by an electric motor of the refrigerant compressor. Further, the refrigerant compressor is characterized by being a scroll type refrigerant compressor.

The insulated rolling bearing of the present invention includes an inner ring and an outer ring, a rolling element, and an insulating bush fitted to the inner peripheral portion of the inner ring or the outer peripheral portion of the outer ring. It has a resin layer formed on the surface of the material, and the metal base material is brought into contact with the inner peripheral portion of the inner ring or the outer peripheral portion of the outer ring to be fitted. In this case, in the insulating bush, the surface of the outer ring or the inner ring in contact with the antibonding surface is made of metal, and the non-contact surface is made of a resin layer. You can prevent eating. Further, since the bearing main body and the insulating bush have an integrated structure, it is possible to prevent the insulating bush from rotating (sliding) relative to the bearing main body and the shaft, and it is possible to prevent wear of the insulating bush. As a result, it is possible to prevent a gap from being generated between the bearing main body and the shaft, and it is possible to prevent vibration and abnormal noise of the entire compressor even when used in a refrigerant compressor or the like.

Further, according to the insulated rolling bearing of the present invention, it is not necessary to increase the thickness of the raceway ring, and the device can be miniaturized. Furthermore, without using rolling bearings filled with conductive grease, it is possible to improve the reliability of the refrigerant compressor by suppressing bearing damage due to bearing electrolytic corrosion and insufficient oil supply with an inexpensive structure. it can.

Since the base resin of the resin layer is PTFE resin, it has excellent heat resistance and chemical resistance. Further, since the resin layer contains 10% by mass to 30% by mass of glass fibers with respect to the entire resin layer, creep resistance can be improved.

It is sectional drawing which shows an example of the refrigerant compressor using the insulating rolling bearing of this invention. It is an enlarged sectional view of the insulation rolling bearing of FIG. It is a perspective view which shows an example of the insulation bush of the insulation rolling bearing of this invention. It is a perspective view which shows another example of the insulation bush of the insulation rolling bearing of this invention.

The refrigerant compressor provided with the insulated rolling bearing of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of a refrigerant compressor. Although FIG. 1 shows a positive displacement scroll compressor as the refrigerant compressor, the refrigerant compressor to which the insulated rolling bearing of the present invention is applied is not limited to the scroll type, and the rotary type, the reciprocating type, and the like. It can also be applied to other compression type positive displacement compressors such as the screw type. Further, it can be applied to both a horizontal refrigerant compressor and a vertical refrigerant compressor.

As shown in FIG. 1, the compressor 1 is composed of a fixed scroll 2, a center housing 3, and a motor housing 4. An iron shaft 5, which is a rotating shaft, is rotatably supported in the center housing 3 and the motor housing 4 via a main bearing 18 and an auxiliary bearing 21. A balance weight 6 is attached to the shaft 5, and the shaft 5 and the balance weight 6 form a rotating member.

The center housing 3 has a bearing support portion 3a for installing a main bearing 18 composed of rolling bearings, and a support portion 3b extending in the outer diameter direction from the bearing support portion 3a and fixing the fixed scroll 2. The main bearing 18 is fitted into a through hole formed in the center of the bearing support portion 3a.

The fixed scroll 2 includes a substrate 2a and a scroll wrap 2b that stands vertically from the substrate 2a. Further, a suction port 2c is provided on the outer peripheral portion of the fixed scroll 2. The movable scroll 7 includes a substrate 7a and a scroll wrap 7b vertically erected from the substrate 7a, and a discharge port 7d is provided at the center. Further, a boss portion 7c is provided so as to project vertically in the center of the substrate 7a on the anti-scroll wrap side, and a swivel bearing 8 composed of a slide bearing is press-fitted into the boss portion 7c.

A compression chamber 10 is formed by engaging the fixed scroll 2 and the movable scroll 7, and the movable scroll 7 swivels to perform a compression operation in which the volume is reduced. Along with the turning motion of the movable scroll 7, the refrigerant gas of the refrigerating cycle is introduced into the compression chamber 10 via the suction pipe (not shown) and the suction port 2c.

The refrigerant gas sucked into the compression chamber 10 is discharged from the discharge port 7d to the discharge chamber 13 through the compression stroke, and then flows from the fluid flow path (not shown) to the motor chamber 14 side. The compressed refrigerant gas flowing to the motor chamber 14 side flows out from the discharge pipe (not shown) to the refrigeration cycle.

A stator 11 as a stator is fixed to the inner peripheral surface of the motor housing 4, and a rotor 12 as a rotor is fixed to the outer peripheral surface of the shaft 5 at a position facing the stator 11. The stator 11 and the rotor 12 form an electric motor, and the rotor 12 and the shaft 5 rotate integrally when the stator 11 is energized.

The shaft 5 is supported by a spindle portion 5a that is rotationally supported by the main bearing 18, an auxiliary shaft portion 5b that is rotationally supported by the auxiliary bearing 21, and a swivel bearing 8 of the movable scroll 7 that is provided at the end of the spindle portion 5a. It is composed of an eccentric shaft portion 5c and the like. The main shaft portion 5a and the sub-shaft portion 5b are formed on the same axis, and the eccentric shaft portion 5c is provided eccentrically with respect to the main shaft portion 5a. Further, the eccentric shaft portion 5c is rotatably supported by the swivel bearing 8 via the sleeve 9. The inner peripheral surface of the swivel bearing 8 serves as a sliding contact surface with the outer peripheral surface of the eccentric shaft portion 5c.

FIG. 15 is a seal ring provided in the groove of the center housing 3 facing the substrate 7a of the movable scroll 7. The outside of the seal ring 15 is a low pressure chamber 16 having a pressure value close to the suction pressure. The space 17 is formed by pressure regulation by a regulating valve and leakage of refrigerant gas from a high pressure region (motor chamber 14 or discharge chamber 13) through a slight gap between the main bearing 18 and the swivel bearing 8 and the shaft 5. The intermediate pressure state is maintained at a lower pressure than the high pressure region and higher than the low pressure chamber 16. By providing a region (space 17) where the pressure is lower than the high pressure region on the back surface of the movable scroll 7, the load generated on the movable scroll 7 on the fixed scroll 2 side due to the pressure applied to the back surface of the movable scroll 7 is reduced. Therefore, the smooth revolution of the movable scroll 7 can be obtained, and the mechanical loss of the movable scroll 7 is reduced.

The main bearing 18 is composed of ball bearings which are rolling bearings, and is arranged on the compression mechanism side of the shaft 5 with respect to the electric motor. The auxiliary bearing 21 is composed of a ball bearing which is a rolling bearing, and is arranged on the anti-compression mechanism side of the electric motor.

The auxiliary bearing 21 is provided in the bearing support portion 4a of the motor housing 4. Specifically, the bearing support portion 4a has an opening 4b for inserting the auxiliary bearing 21 on the motor side, and the auxiliary bearing 21 is inserted through the opening 4b. A cover may be provided to cover the opening 4b of the auxiliary bearing 21.

Next, the insulated rolling bearing which is the auxiliary bearing 21 shown in FIG. 1 will be described with reference to FIG. As shown in FIG. 2, the auxiliary bearing 21 includes a bearing main body having an inner ring 22 and an outer ring 23 which are raceway rings, and a plurality of balls (rolling bodies) 24 interposed between the inner and outer rings, and an inner ring 22. An insulating bush 28 fitted to the inner peripheral portion is provided. The balls 24 are aligned and held at regular intervals by the cage 25. The bearing space around the ball 24 is filled with grease 27, and the bearing space is sealed by the sealing member 26. The inner ring 22, the outer ring 23, and the ball 24 are made of bearing steel such as SUJ2.

FIG. 3 is a perspective view showing an example of the insulating bush. As shown in FIG. 3, the insulating bush 28 is a substantially cylindrical member having a cut portion in a part in the circumferential direction, and is formed on a substantially cylindrical metal base material 28a and an inner peripheral surface of the metal base material 28a. It has a formed resin layer 28b.

In FIG. 2, the insulating bush 28 is press-fitted by bringing the metal base material 28a into contact with the inner peripheral portion on the antibonding side of the inner ring 22. By press-fitting the insulating bush 28 and further inserting the shaft 5 into the shaft hole of the insulating bush 28, the shaft 5, the insulating bush 28, and the inner ring 22 can rotate integrally. When the shaft is rotating, the resin layer 28b comes into contact with the outer peripheral surface of the shaft 5 without sliding. As shown in FIG. 2, the resin layer 28b is interposed between the inner ring 22 and the metal base material 28a and the shaft 5, so that the axial current can be blocked from flowing to the bearing body through the shaft 5.

Another example of the insulating bush is shown in FIG. The insulating bush 28'shown in FIG. 4 is provided with a resin layer 28b on the inner peripheral surface of a flanged cylindrical metal base material 28a. When the insulating bush 28'is fitted to the inner peripheral portion of the inner ring, the flange portion is fitted to the width surface of the inner ring, and the metal base material 28a comes into contact with the width surface.

The thickness of the metal base material and the resin layer is not particularly limited, but it is preferable that the thickness of the metal base material is larger than the thickness of the resin layer. The thickness of the metal base material is preferably 0.5 mm to 5 mm, more preferably 1 mm to 3 mm. The thickness of the resin layer is preferably 0.1 mm to 2 mm, more preferably 0.5 mm to 1 mm.

As the material of the metal base material, a steel plate made of SPCC or the like can be used. Since the resin layer is used in an environment exposed to a refrigerant or a lubricating oil, it preferably has chemical resistance. Specifically, it is preferable to use a polyetheretherketone (PEEK) resin, a polyphenylene sulfide (PPS) resin, or a PTFE resin as the base resin of the resin layer. Among these, it is particularly preferable to use a PTFE resin having excellent chemical resistance. In addition, additives can be appropriately added to the resin layer. As the additive, it is preferable to add a non-conductive reinforcing material (glass fiber or the like) because the creep resistance can be improved.

As a specific form of the resin layer, it is preferable to use PTFE resin as the base resin and glass fiber as the additive. The glass fiber preferably contains 10% by mass to 30% by mass of the entire resin layer.

The insulated rolling bearing of FIG. 3 can be obtained by, for example, the following method. First, a resin sheet having a thickness of 0.5 mm, which is a mixture of PTFE resin and glass fiber, is adhered to the surface of a steel plate having a thickness of 1 mm such as SPCC. The adhesive surface of the metal base material is preferably roughened by the roughening treatment. The surface of the roughened metal base material plays a role of firmly adhering the resin layer (including the resin sheet) by the anchor effect. As the roughening treatment, a mechanical roughening method such as a shot blast method, an electrical roughening method such as a glow discharge or a plasma discharge treatment, or a chemical roughening method such as an alkaline treatment can be adopted. Then, after cutting the composite plate of the metal base material and the synthetic resin sheet into a rectangle of a predetermined size, the composite plate is bent into a cylindrical shape so that the resin sheet is on the inner peripheral side, thereby forming a winding bush (insulating bush). ) Is obtained.

The resin layer of the insulating bush is not limited to the case of being formed of a resin sheet, but can also be obtained by applying a molten resin composition to the surface of a metal base material and drying it, or by injection molding.

By press-fitting the obtained insulating bush into the inner peripheral portion of the inner ring of the bearing portion, the insulated rolling bearing of FIG. 2 can be obtained. The press-fitting allowance is, for example, 10 μm to 60 μm, preferably 20 μm to 50 μm. If the press-fitting allowance is less than 10 μm, the inner ring and the insulating bush may rotate relatively as the shaft rotates. Further, if the press-fitting allowance is more than 60 μm, the roundness of the raceway surface of the insulating bush, that is, the bearing surface formed of the resin layer may deteriorate.

As described above, when the insulated rolling bearing of the present invention is used in the refrigerant compressor of FIG. 1, the insulating bush is fitted to the inner peripheral portion of the inner ring, but the present invention is not limited to this. For example, when the bearing used in the refrigerant compressor has an outer ring rotation configuration, an insulating bush can be fitted to the outer peripheral portion of the outer ring. In this case, the insulating bush is fitted so that the metal base material comes into contact with the outer peripheral portion of the outer ring, and the outer peripheral surface of the insulating rolling bearing becomes a resin layer.

In the above figure, ball bearings are shown as auxiliary bearings, but tapered roller bearings, cylindrical roller bearings, self-aligning roller bearings, needle roller bearings, thrust cylindrical roller bearings, thrust tapered roller bearings, thrust needle roller bearings, and thrusts. It can also be applied to self-aligning roller bearings.

The configuration of the refrigerant compressor is not limited to the configuration shown in FIG. For example, an oil supply pump connected to an oil sump may be provided at the end of the shaft 5 in FIG. 1, and an oil passage may be formed in the shaft 5 so as to penetrate in the axial direction. According to this configuration, the swivel bearing, the main bearing, and the auxiliary bearing can be lubricated by supplying the oil in the oil sump (refrigerator oil) to the oil passage via the oil supply pump.

The insulated rolling bearing of the present invention can be widely used as an electrolytic corrosion prevention bearing that can prevent electrolytic corrosion and prevent a gap between the shaft and the raceway ring.

1 Compressor 2 Fixed scroll 3 Center housing 4 Motor housing 5 Shaft 6 Balance weight 7 Movable scroll 8 Swivel bearing 9 Sleeve 10 Compression chamber 11 Stator 12 Rotor 13 Discharge chamber 14 Motor chamber 15 Seal ring 16 Low pressure chamber 17 Space 18 Main bearing 21 Sub-bearing (insulated rolling bearing)
22 Inner ring 23 Outer ring 24 Ball 25 Cage 26 Sealing member 27 Grease 28 Insulation bush

Claims (6)

An insulated rolling bearing comprising an inner ring and an outer ring, a plurality of rolling elements interposed between the inner and outer rings, and an insulating bush fitted to the inner peripheral portion of the inner ring or the outer peripheral portion of the outer ring.
The insulating bush has a substantially cylindrical metal base material and a resin layer formed on the inner peripheral surface or the outer peripheral surface of the metal base material, and the insulating bush has the metal base material side of the inner ring. An insulated rolling bearing characterized in that it is fitted in contact with an inner peripheral portion or an outer peripheral portion of the outer ring. The insulating rolling bearing according to claim 1, wherein the insulating bush is a wound bush having a cut portion in a part in the circumferential direction. The insulated rolling bearing according to claim 1 or 2, wherein the base resin of the resin layer is a polytetrafluoroethylene resin. The insulated rolling bearing according to claim 3, wherein the resin layer contains 10% by mass to 30% by mass of glass fibers with respect to the entire resin layer. The insulated rolling bearing is any one of claims 1 to 4, wherein the insulated rolling bearing is a bearing that is used in a refrigerant compressor and rotationally supports a shaft that is rotationally driven by an electric motor of the refrigerant compressor. Insulated rolling bearings as described. The insulated rolling bearing according to claim 5, wherein the refrigerant compressor is a scroll type refrigerant compressor.

Images